Successful treatment with combined chemotherapy of two adult cases of hemophagocytic lymphohistiocytosis in recipients of umbilical cord blood cell transplantation.

Hemophagocytic lymphohistiocytosis (HLH), which occurs during the early period following allogeneic hematopoietic stem cell transplantation (HSCT), is often difficult to diagnose. It is characterized by severe clinical manifestations and high mortality. Despite current therapeutic approaches, outcomes remain poor. Here, we summarize the cases of two patients who experienced engraftment failure and subsequently developed hematopoietic stem cell transplantation-hemophagocytic lymphohistiocytosis (HSCT-HLH). Both patients had high-risk hematological malignancies for which they underwent umbilical cord blood transplantation (UCBT) at our institution. Based on the presence of massive hemophagocytosis in their bone marrow specimens and the results of chimerism analysis, diagnosis of HSCT-HLH was made in both cases. A single infusion of low-dose etoposide was administered immediately to each patient. Four days after the injection, therapeutic efficacy was evaluated. As both cases showed an insufficient response to etoposide, we added vincristine and a medium dose of prednisolone. Clinical symptoms rapidly improved and stable engraftments were observed within a week. The first and second patients were alive 1008 and 232 days after UCBT, respectively. The combined use of low-dose etoposide and vincristine plus prednisolone appears to be a promising treatment option for HSCT-HLH, without serious adverse side effects.